In recent years, many kinds of ferroelectric materials and piezoelectric materials have been developed and used for a supersonic, an optical device and a memory and the like. In association with it, a development of methods of measuring a residual polarization distribution of the ferroelectric material and a local anisotropy of the piezoelectric material has been advanced. With regard to the development in this field, the inventors of this application have developed a scanning nonlinear dielectric microscopy (SNDM) as a technique for a purely electrical detection of a polarization distribution of a material and a local anisotropy without any disturbance of a shield effect caused by free charges disposed on a surface.
The SNDM is the technique for detecting the condition of the polarization and the local anisotropy from a distribution measurement of a nonlinear dielectric constant of a material. As the technique of the SNDM, the development has been successively advanced such as a distribution constant type probe using a coaxial resonator and a small concentrated constant type probe using an LC resonator. In this way, according to the SNDM, nondestructive measurement can be performed on the polarization distribution of a dielectric substance in an extremely small area. On the other hand, according to the SNDM, the polarization can be controlled by applying a predetermined electric field.
The method using the SNDM converts a capacitance change of a dielectric domain (i.e. small area of the dielectric substance) into a frequency change in principle. Thus, a distribution in a polarization direction of the dielectric substance is easily determined. However, there is a problem in a quantitative measurement of a dielectric constant. In order to solve this problem and measure a distribution of a dielectric constant, the inventor of this application et al. proposed that the quantitative measurement of the dielectric constant could be attained by using a tungsten probe placed vertically to a surface of a dielectric substance, using an analysis model simulated with a shape of a prove tip formed by an electrical field polishing as a sphere and also determining a floating capacitance in a measurement system from a measurement of a dielectric sample whose dielectric constant had been known in advance and thereby canceling out the floating capacitance on the basis of it. However, this method could cope with only the measurement in a rough region until a μm order at most because of the limit of a resolution in the measurement system.